Method of making copper-lead bearings



Aug. 20, 1940. w. HESSENBRUCH ET AL 2,212,473

METHQD OF MAKING COPPER"LEAD BEARINGS Filed Sept. 14, 1938 havenians:

Patented Aug. 20, 1940 PATENT OFFICE METHOD OF MAKING COPPER-LEADBEARINGS Werner Hossenbruch and Wilhelm Rohn, Hananon-the-Main, GermanyApplication September 14, 1938, Serial No. 229,973 In Germany November6, 1936 2 Claims. (Cl. 29-1495) This invention relates to copper-leadbearings which are especially adapted for the bearings in aeroplanes.

For high duty bearings alloys of copper and lead have been foundspecially suitable. Such bearings usually consist of a supporting steelshell into which a thin lining of the copperlead alloy has been cast.

Owing to the large difference between the melting points of copper andlead it is extremely difficult to have full control of the structure ofthe solidified alloy and to obtain a homogeneous and line distributionof the lead particles through the skeleton of the copper. Very l5 oftena large percentage of a series of finished bearings must be scrappedafter X-ray examination has shown that the lead has segregated in someheavy particles and left other areas without the necessary fineparticles of lead. Another drawback of the method hitherto used is thatthe cast layer must first be at least of an inch thick, it beingimpossible to cast only a thin lining of less than 3% or ,6 inch of thecopper lead alloy on or in a steel shell, and that heavy risers orfeedheads must be used. 95 per cent of the alloy originally cast has tobe cut off as risers and machined from the surplus of the thickness ofthe lining cast. Therefore the weight of metal really cast is to timesthe weight of the final lining in the bearing.

According to the present improved method the copper skeleton of acopper-lead bearing is made of a copper-wire cloth. By suitable choiceof the diameter of the wire and the width of the meshes of thecopper-wire cloth the structure of the copper lead bearing can beaccurate- 1y controlled with regard to the proportion of copper to leadand with regard to the size and regular distribution of the leadparticles. For making such bearings one or more layers of copper-wirecloth are wound on or in the steel shell (which may be superficiallytinned) and then impregnated or infiltrated with the lead by dipping thewhole into molten lead. By this method copper-lead linings can beobtained with a ratio of copper to lead of about 20 to 80 up to about to50. If a lower percentage of lead is desired the copper-wire cloth canfirst be passed through rollers in order to 50 flatten the cross pointsof the longitudinal and transverse wires. The distance between the twosurfaces of a wire cloth is usually twice the thickness of the wiresbecause at each crossing two wires are lying across one another. Bypassing the cloth through rollers the crossings can be flattened out andany distance between the two surfaces of the rolled wire cloth betweentwice the diameter of the wires and about 0.7 of the original diameterof the wire can be obtained. By using such rolled wire-cloth for thehere described method a ratio of copper to lead of up to to 15 can beobtained.

In a copper-lead bearing made according to this method the weight ofcopper and lead employed is only slightly above the weight of the twometals in the finished bearings.

To finish the bearing for use it is not necessary to machine any surplusout of the crude bearing but the so called press finishing can be usedwhich consists in pressing a mandrel or a ball, the diameter of whichcorresponds to the desired final diameter of thebearing, through theopening of the bearing.

To obtain an exact fit the outer side of the steel shell may be machinedon the lathe.

According to the method described copper and lead are not meltedtogether but the copper is used in a form of a woven cloth and only thelead is melted and brought into the pores of the cloth in liquid form.This provides a very important advantage as it is possible in this wayto separately alloy both the copper and the lead in any suitable ordesirable way. For instance, instead of making the skeleton of thebearing of copper, it may be made of tin-copper-bronze orphosphorus-copper-bronze or beryllium-copper-bronze, and the lead may bealloyed with antimony or bismuth or tin or sodium or calcium etc.

Whereas the ordinary method of preparing lead-copper bearings does notallow any accurate control of the structure and arrangement of theparticles or of the composition of the skeleton and the composition ofthe segregated particles, the improved method permits of full control ofall these important details, and out of one hundred bearings producedone hundred perfect bearings can be obtained, whereas according to themethod used up to now out of one hundred bearings made very often 20 tohad to be scrapped after X-ray examination. The results of this newmethod are so certain that the expensive X-ray examination of thefinished bearings can be dispensed with.

The annexed drawing shows a cross-section of a bearing made according tothe present invention. a is the steel shell, b the copper wire netting,and c the lead or lead alloy filling the pores between the wires.

We claim:

l0 tween particles containing copper.

2. The method of making copper-lead bearings which comprises passing oneor more layers of a cloth woven from a wire containing copper throughrollers, combining the said layers with a steel shell, and thereafterfilling the pores oi the copper cloth with a. molt'enmetal consisting ofa lead alloy in such a manner that on the surface of the bearingparticles of a metal substantially consisting of lead are insertedbetween particles containing copper.

WERNER HESSENBRUCH. WILHELM ROHN.

